The Chemistry of Light-Production in Luminous Organisms. 205 



light-production in animals is not connected with the ordinary oxidases 

 (peroxidases) (see p. 232). 



As in all other organic tissues, catalase is also present in the juice of 

 Cavernularia. 



TEMPERATURE. 



The juice of Cavernularia still gives a good light at C., as do pieces 

 of the colony if stimulated. 



On raising the temperature, the light of Cavernularia juice disappears 

 at 52 and does not reappear on cooling. Pieces of the colony slowly 

 heated begin to light spontaneously at about 40. 



The light of Noctiluca (2) disappears at 48, Cypridina at about 54, 

 a hydroid (Sertularia sp.) at 54, the firefly (Luciold) at 42, and 

 luminous bacteria at 38. 



PHOTOGENIN AND PHOTOPHELEIN. 



Unlike the firefly, Cypridina, and Pholas dactylus, it is impossible to 

 separate the luminous juice of Cavernularia into two substances, 

 photogenin and photophelein (lucif erase and luciferin), one destroyed 

 by boiling, the other not, which will give light when mixed. We can 

 not, for instance, cause light to appear in Cavernularia juice which has 

 stood until the light has disappeared by adding fresh luminous Caver- 

 nularia juice heated to boiling and then cooled; neither can we obtain 

 light by adding juice heated to temperatures below boiling (88, 81, 

 71, 61, or 52 C.) and then cooled. 



Another species of pennatulid, Pennatula sp., as also Noctiluca and 

 the squid Watasenia scintillans, behaves as does Cavernularia. None 

 of these organisms gives the photophelein-photogenin (luciferin- 

 luciferase) reaction, for reasons at which we can only guess. The 

 photogenin or photophelein may be, either of them, very unstabile, or 

 there may be sufficient photophelein to use up all the photogenin. The 

 evidence in this case seems to indicate that the photophelein is unstabile, 

 as we can obtain a faint light with Cypridina photophelein or firefly 

 photophelein (both prepared with sea-water) and the non-luminous 

 Cavernularia juice (photogenin) . Pennatula and Noctiluca photophelein 

 gave negative results with Cavernularia juice, and vice versa. 



TABLE 11. Effect of standing on light-producing power of Cavernularia juice. 



Juice + water Bright light. 



Juice 12 hours old at 20 C. + water Bright light. 



Juice 24 hours old at 20 C. + water Fair light. 



Juice 48 hours old at 20 C. + water Faint light. 



Juice 72 hours old at 20 C. + water None. 



The question may be asked, what substances are able to cause light 

 to appear in the juice of Cavernularia which has stood until completely 

 dark? Usually 4 to 6 hours are sufficient time for the juice to lose its 

 luminescence. It is still capable of giving out a bright light if we add 

 fresh-water (but not sea-water) to it, and it retains this potentiality 



